Clothes dryer with improved refrigerant circuit

ABSTRACT

A dryer comprises a cabinet, drying drum and heat supply duct and refrigeration circuit. The refrigeration circuit includes a compressor, condenser, metering valve and an evaporator jacketed within an evaporator jacket containing a liquid. The heat supply duct houses the condenser and a resistive heat element. A blower passes air over the condenser and the resistive heat element and into the dryer drum. A temperature sensor is housed within the heat supply duct and positioned to measure the temperature of air entering the drum. The sensor is in communication with a control circuit. The control circuit switches the resistive heat element on and off in response to the sensing of air entering the dryer drum. In one embodiment the liquid jacketing the evaporator is sourced from a washing machine cold water supply line. In a second embodiment the liquid jacketing the evaporator is sourced from a geothermal heating system.

CROSS REFERENCE TO RELATED APPLICATION

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM ON COMPACT DISC

Not applicable.

FIELD OF INVENTION

The present invention relates to a clothes dryer and, more particularly, to a clothes dryer having an improved refrigerant circuit.

BACKGROUND OF THE INVENTION

A traditional clothes dryer operates by blowing heated air into a tumbler (a/k/a drum) containing damp laundry. Typically, the air entering the dryer is heated by passing through a resistive coil that heats up when electrified. The heated air entering the tumbler is relatively hotter and dryer than the laundry and thus the moisture in the clothes is imparted to the air in the tumbler. The moist air is discharged from the dryer via an exhaust chute that typically leads outside of the home or at least the room in which the drying occurs. Though the traditional dryer does well to dry clothes, it requires a relatively large amount of energy to operate effectively.

Recent developments in dryer technology has seen the inclusion of an integral heat pump or refrigeration circuit in the dryer as a way to augment the heating of the air entering the dryer. As with the traditional dryer, the newer dryer includes a resistive coil in the air intake duct that heats up when electrified and transfers heat to passing air. However, in the newer type of dryer, the air intake duct also includes a condenser (as known in refrigerant circuit technology). The condenser is fed a refrigerant under relatively high pressure which changes phase in the condenser thereby giving off heat. The heat emitted by the condenser is absorbed by the air entering the dryer drum.

The newer type dryers have also been modified to not only heat air going into the dryer drum, but also to treat the exhausted moist air and scavenge the moisture from it. In this even more complicated type of dryer, the heated moist air is blown over an evaporator (again as known in a refrigeration circuit). The evaporator causes the contained refrigerant to change from a low pressure liquid to a low pressure vapor. In doing so, the evaporator causes the hot moist air removed from the dryer drum to cool and condense. The exhausted air now released of its moisture is reheated and recirculated back into the dryer for drying purposes.

The use of an evaporator to remove moisture from air removed from the dryer drum means that the newer type dryer does not need the exhaust duct of the traditional dryer for discharging air out of the dryer. Such a dryer reportedly has a higher energy efficiency compared with the exhaust type clothes dryer, but ostensibly suffers from the fact that it takes a longer time to dry laundry. In addition, including an evaporator with a dryer means that the dryer should provide for some means to drain or remove the condensation that is drawn out of the air. Failing to do so could lead to issues of rust, floor slipperiness or conditions that can cause electric shock. Another problem with dryers that employ an evaporator to cool and dehumidify air, results from the dumping of refrigerated air in the same room the drier is located. By way of example, if a laundry room with the dryer is desired to be 70 degrees, having air chilled by the evaporator will require utilizing another heat source to maintain the room at 70 degrees. Lastly, in order for a dryer that employs an evaporator to cool and dehumidify air to work properly, the evaporator must efficiently draw heat and moisture out of the air. To do so means that the dryer must incorporate an air filter system and the evaporator must be regularly cleaned.

SUMMARY OF THE INVENTION

The present invention solves the problems of the prior art by providing for a dryer that incorporates a refrigeration circuit that includes an evaporator jacketed in liquid (a/k/a liquid exchange evaporator). The present invention clothes dryer includes a cabinet with a drying drum and a heat supply duct. A condenser is housed within the heat supply duct. The condenser is part of a refrigerant circuit that includes the condenser, an evaporator, a compressor fluidly disposed between the condenser and the evaporator in a segment of the circuit and a metering device fluidly disposed between the evaporator and the condenser in a segment of the circuit that does not include the compressor. The circuit is adapted to receive a refrigerant that is used by the condenser to heat air in the heat supply duct. The dryer further includes a blower adapted to pass air over the condenser and into the dryer drum. By providing for a liquid exchange evaporator, a jacketing liquid can be used to heat the evaporator instead of air.

In one embodiment, the dryer includes a thermo-sensor that measures the temperature of air entering the dryer drum from the heat supply duct. The dryer may also include a resistive heating element housed in the heat supply duct along with the condenser such that the air moved by the blower passes over the resistive heating element and the condenser on its way into the dryer drum. The resistive heating element can be used to augment the heating provided by the condenser. In another embodiment the jacketing liquid is sourced from the cold water side supply of the washing machine. In another embodiment, the jacketing liquid can be sourced from a geothermal heating system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing a clothes dryer having the improved refrigerant system according to an exemplary embodiment of the present invention that uses water from a washing machine cold water supply to jacket the evaporator.

FIG. 2 is a view schematically showing a clothes dryer having the improved refrigerant system according to an exemplary embodiment of the present invention that uses water from a geothermal heating system to jacket the evaporator.

FIG. 3 is a view showing an embodiment dryer having the improved system in which the liquid surrounding the evaporator is sourced either from the cold water supply for an adjacent washing machine or from a geothermal heating system.

DETAILED DESCRIPTION

A clothes dryer including the improved refrigerant system according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIGS. 1-3 show embodiment clothes dryers 1 having an improved refrigeration circuit 2 according to the present invention. The embodiment dryer system of FIGS. 1 and 3 includes cabinet 3 with drying drum 4 and heat supply duct 5. A condenser 6 and electric resistive heating element 14 are housed within heat supply duct 5. In the embodiment dryer of FIG. 3 the lower right portion of the dryer 1 below drum 4 houses electric heating element 14 and condenser 6 and constitutes part of heat supply duct 5. As shown in FIG. 3, a segment (shown in phantom dashed lines) of duct 5 extends up the rear of cabinet 3 to air ingress point 16 of drum 4. Condenser 6 is part of refrigeration circuit 2 that also includes evaporator 7. As schematically shown in FIG. 1, compressor 8 is fluidly disposed between condenser 6 and evaporator 7 in a segment A of the circuit 2. Metering device 9 is fluidly disposed between evaporator 7 and condenser 6 in the circuit segment B that does not include compressor 8. Circuit 2 is adapted to receive a refrigerant that is used by condenser 6 to heat incoming air 10 in heat supply duct 5. As shown in the drawings, the refrigerant assumes a phase that varies based upon its stage (location) in refrigeration circuit 2. Between compressor 8 and condenser 6 the refrigerant is in the form of a high pressure vapor 24. Between condenser 6 and metering valve 9 the refrigerant is in the form of a high pressure liquid 25. Between metering valve 9 and evaporator 7 the refrigerant is in the form a low pressure liquid 26. Between evaporator 7 and compressor 8 the refrigerant is in the form of a low pressure vapor refrigerant 27.

Dryer 1 further includes blower 11 adapted to pass incoming air 10 over condenser 6 and heating element 14 and into dryer drum 4. Blower 11 also operates to move exhaust air 12 out through exhaust duct 13. Heat supply duct 5 also includes sensor 15 proximal to the air ingress point 16 of drum 4. Sensor 15 is a temperature sensor that is part of a thermostat system that senses the temperature of air entering drying drum 4.

Compressor 8 can be a rotary, reciprocating or scroll compressor and should preferably be inverter driven. Condenser 6 can be a standard aluminum or copper condenser. Metering device 9 can be a cap tube, piston or expansion valve. Evaporator 7 is a liquid exchange evaporator housed within a jacket 29 holding a jacketing liquid 17 that is used to heat the refrigerant in the evaporator instead of air.

The refrigerant system has high efficiency compared with a clothes dryer employing only a resistive heating element as a heat source. By including adjunct resistive heating element 14 in heat supply duct 5 through which air is introduced into drum 4, additional heat can be added to that from the refrigerant circuit allowing the dryer to operate efficiently in several modes.

To operate the dryer shown in FIGS. 1 and 3, the user places damp laundry in drum 4 and selects a drying mode and starts dryer 1. Drum 4 begins rotating. Blower 11 begins pulling air 10 through condenser 6 and resistive heating element 14 in heat supply duct 5 and on in to drum 4. When dryer 1 is started, compressor 8 starts and refrigerant starts cycling through refrigeration circuit 2. Upon this call for heat, compressor 8 sends hot refrigerant vapor 24 into condenser 6. Condenser 6 begins emitting heat. Blower 11 cools condenser 6 by passing room temperature air over the coils of condenser 6 which gives up its heat to the passing air. In the process the hot refrigerant vapor 24 in condenser 6 is converted into liquid 25. After incoming air 10 cycles through drum 4 it becomes moisture laden exhaust air 12. Blower 11 moves exhaust air 12 through dryer exhaust duct 13 and out of dryer 1.

Air temperature after passing condenser 6 will be 105 to 110 degrees Fahrenheit assuming the dryer is located in a location with room temperature air of 70-75 degrees Fahrenheit. As shown in the figures, incoming air leaves the condenser and enters the area surrounding the electric resistive heat element. The electric heat element can be a 3-4 kilowatt heater that can raise the air temperature to 180-200 degrees Fahrenheit. Resistive heating element 14 is controlled by a temperature control circuit (not shown) in electrical communication with sensor 15 probe located in heat supply duct 5 proximal to ingress point 16 leading into drum 4. Resistive heating element 14 will cycle with the temperature control circuit, but refrigeration system 2 will run constantly while the system is calling for heat.

As part of the refrigeration circuit, refrigerant liquid 25 leaving condenser 6 goes to metering device 9 which transforms the refrigerant liquid from a high pressure liquid 25 to a low pressure liquid 26. From there the low pressure liquid 26 goes into evaporator 7, which changes the low pressure liquid 26 to a low pressure vapor 27 and returns the vapor 27 to the compressor 8. In contrast to the prior art dryers, evaporator 7 is a liquid exchange evaporator in which the refrigerant lines are jacketed by a liquid 17 contained within jacket 29 instead of air. Evaporator 7 can be coaxial, a tube within a tube or brazed plate. Brazed plate would be the best for light weight and space savings purposes. Jacket 29 is preferably shaped and sized in accordance with the shape and size of evaporator 7.

Preferably, the jacketing liquid 17 for the evaporator can be sourced from the cold water supply 21 for the washing machine. This arrangement is depicted in FIGS. 1 and 3. If tied into the cold water supply 21, then the system should include motorized water valve 20 that will open and close with compressor 8 operation to remove excess water 17 around the evaporator and allow it to drain, preferably into the drain 22 that receives the washing machine discharge. Specifically, when there is a call for compressor operation, motorized water valve 20 will open. Valve 20 can be located near the exit for the cold water jacketing on the evaporator. The amount of water being used will be determined by the BTUs of the compressor. Because the water 17 in the cold water supply line is already pressurized as it jackets the evaporator, once valve 20 opens, the water will discharge. Preferably, because the dryer is using the washing machine cold water supply line, the dryer can discharge its jacketing water 17 into the same drain that receives the washing machine discharge.

FIG. 2 shows a schematic of an embodiment clothes dryer 1 similar to that shown in FIG. 1 and described above, except that the jacketing liquid for the evaporator is tied into (sourced from) a geothermal heating system that includes geothermal supply line 18, discharge line 19 and geothermal heating system 23. If an owner wishes to use this system, the jacketing liquid 17 can flow through the closed loops of geothermal heating system 23, which would be most efficient. The system can include motorized valve 20, which can be locked in an open position so that the control power that runs valve 20 will also operate a circulating pump 28 that will circulate liquid from the geothermal unit ground loops within system 23 to evaporator 7. In overall appearance, the dryer schematically shown in FIG. 2 will match the dryer shown in FIG. 3, the only difference being the supply and drain structures and connection, which are shown in FIGS. 1 and 2.

The use of a liquid jacketed evaporator to modulate refrigerant phase in the dryer yields a highly efficient dryer that does not produce damaging and dangerous condensation in a laundry room environment. Additionally, using a liquid jacketed evaporator also reduces the problem of having to warm and cool ambient air in the laundry room because of the fluctuations caused by dryer operation. The liquid jacketed evaporator also reduces the need to have to clean the evaporator to remove room air particulates accumulating on the evaporator.

While the present invention has been described in the context of specific embodiments thereof, other alternatives, modifications, and variations will become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims. 

The invention claimed is:
 1. A clothes dryer comprising: a cabinet, a drying drum and a heat supply duct; a refrigeration circuit, the refrigeration circuit including a compressor, a condenser, a metering valve and an evaporator, the evaporator being jacketed within an evaporator jacket containing a liquid; the condenser and a resistive heat element housed within the heat supply duct; a blower adapted to pass air over the condenser and the resistive heat element and into the dryer drum; a temperature sensor housed within the heat supply duct, the temperature sensor positioned to measure the temperature of air entering the dryer drum and in electrical communication with a control circuit; and the control circuit adapted to switch the resistive heat element on and off in response to the sensing of temperature of air entering the dryer drum.
 2. The dryer of claim 1 wherein the liquid within the evaporator jacket is water sourced from a washing machine cold water supply line.
 3. The dryer of claim 2 further including a valve configured to drain the water within the jacket.
 4. The dryer of claim 1 wherein the liquid within the evaporator jacket is sourced from a geothermal heating system. 